Insulating material



March 8, 1938. c. L. NORTON INSULATING MATERIAL Filed Feb. 24, 1936 iJfiuenior: M 5.1% 3 V f Patented Mar. 8, 1938 states nane,

ENSULATING MATERIAL .Charles L. Norton, Boston, Mass.

ApplicationFebr-uary 24, 1936, Serial No. 65,441 3 Claims. (or 106-19)This invention relates to insulating material for use in walls, roofsand partitions of houses and other buildings for the purpose ofpreventing the transmission therethrough of heat and sound, and forinsulating heated surfaces generally from loss of heat. i

If a building or other structure is to' be insvlated during the processof construction, there are a wide variety of structural elements in theform of sheets, blocks, or the like which can be used for this purposewith more or less satisfactory results. These. however, cannot, as arule, be conveniently employed in buildings already built, and in suchcases a common method of house insulation is to introduce someinsulating powder or fibre into the wall or the like to fill up thespace between the interior plaster or. other finish and the boarding orthe like which forms the outside of the wall. This insulating materialis usually introduced by blowing, in accord- 2 ance with the systemdescribed in the Slayter.

Patent No. 1,728,837. Materials'which have been used for this purposeinclude slag wool, rock wool, cork'dust, sawdust, comminutecl cornhusks, air blown gypsum, and other mixtures of powder or fibres.

There are numerous objections to all of these materials as now commonlyused. In the first place, when they are blown in they pack very lightlyand tend to settle later, leaving uninsulated portions at the top. Sofar as I am aware, no remedies have been successful in preventing this.The vegetable fibres and similar organic materials are furtherobjectionable because of their combustibility, because they ofierfavorable conditions for the breeding of vermin, and be" cause many ofthem have a tendency to ferment malodorous and otherwise offensiveconditions.

40 When silicious powders and fibres are used, particularly when slagwool or rock wool is introduced in the usual manner by blowing, there isa tendency for finely divided portions of this vmaterial to filterthrough the cracks in the plaster or down around the box boards and outinto the rooms, producing a dusty and unhealthy condition; atmospherecontaining silicious dust being well known. Inturnesced material, such.as frothy masses or lumps of sodium silicate, has been used to someextent for this purpose, but this has not been entirely satisfactorysince the material is not dust free, either in handling or in thepresence of drafts and tremors such as occur in the deleterious effectsof breathing most buildings; and even in the process of introducing thematerial into the wall there is a tendency, because of its very greatfriability, for the lumps to be broken up and reduced to dust, at leastin part.

It is believed that an ideal insulating material for wall filling shouldhave the following characteristics: 1) It should'have high thermalinsulating value. (2) It should be non-combustible or at least incapableof supporting its own combustion. (3) It should be absolutely free frompossibility of decomposition or fermentation or the breeding and housingof vermin. (4) It should be of low density and light in weight. (5) Itshould be in the form of nodules or lumps which are sufiiciently hard,at least upon their exterior, not to be dusty and the source of anypowder or dust which may escape into the rooms. (6) The nodules or lumpsshould be sufliciently rigid not to pack down. (7) It should be of sucha character as to prevent the transmission of heat by radiation as wellas by conduction. (8) It should be capable of being introduced intoproper position in the walls without blowing merely by a pouring,shoveling, or similar operation.

2 l. have found that an insulating material meeting all of the aboverequirements may comprise a loose mass of nodules of a porous heatinsulating material, preferably an intumesced soluble silicate, saidnodules having smooth, hard surfaces or exterior crusts which are denserthan their highly porous or cellular interiors; and the presentinvention consists in the provision of such a material.

The invention will best be understood from the following description ofseveral illustrative forms of such a material and the methods ofproducing the same, all as illustrated in the accompanying drawing,these, however, having been chosen for purposes of exemplificationmerely, as it will be obvious to those skilled in the art that theinvention, as defined by the claims hereuntoap pended, can be otherwiseembodied and practiced without departure from the spirit and scopethereof.

In said drawing:

Figs. 1, 2 and 3 are sectional views illustrating three steps in theproduction of insulating mate rial in accordance with the invention.

Fig. 4 is a sectional view of one of the resulting nodules.

Fig. 5 is a perspective view thereof.

Fig. 6 is a sectional view of a-nodule such as that shown in Fig. 4after having been subjected to further treatment.

Fig. 7 is a sectional view of a nodule produced in a different way.

Fig. 8 is a sectional view of the nodule shown in Fig. 7 after havingbeen subjected to further treatment.

Fig. 9 is a perspective view of a further modification. V T

Fig. 10 is a fragmentary vertical sectional view of an insulated wall. 7

In Figs. 3, 4, 6 and 8 the proportions are somewhat distorted, thethickness of the crusts and coatings hereinafter referred to beingexagger I ated for clearness of illustration.

' In accordance with one mode of practicing the invention such a noduleis provided with ahardr In accordance with the invention, small massesof a combustion resisting material intumescible by heat, such as alum ora soluble silicate, preferably sodium silicate, may be heated to causethe same to intumesce or froth up into the form of an expanded nodule.If this be done in the open or without restraint, the intumescence willbe substantially uniform throughout, as indicated in the case of thenodule I5 shown in Fig. 7. Such a'nodule is light and of high porosityand high insulating qualities but is so friable as to be of slightpractical value, as above explained.

ened surface or crust I 6, Fig. 8, which enables it to resist breakingand also increases its insulating qualities. Such acrus't can beappliedin a variety of ways, as by coating with varnish or plaster, orwith a solution of unintumesced soing the nodule momentarily to theaction of a, flame.

dium silicate or the like which is subsequently dried at such a rate asnot to cause intumescence, or by fusing or flashing the surface bysubject- While a satisfactory insulating material can be produced asabove described, the preferred procedure is as illustrated in Figs. 1 to3. If the intumescencebf the sodium silicate or other material, takesplace in a confined space too small for its complete natural expansion,it results in naturally formed, hard, almost vitreous crust of a muchhigher density than the interior, and is strong enough to be capable ofconsiderable handling without fracture or substantial abrasion. In Figs.lto 3 there is shown a mold II composed of two separable sectionsproviding between them preferably spherical mold cavities I8 of suitablesize. Said mold is heated to a temperature of from 650 F. to 800 F. andopened, a small quantity or mass I 9 of sodium silicate introduced intoeach of themold cavities I8, and the mold closed, as shown in Fig. 1.Said sodium silicate is preferably in the dry form, that is to say,containing not substantially more than 20% of water, although silicatecontaining a greater proportion of water can be used. The quantityintroduced into each mold cavity, while suflicient, if completelyintumesced, to produce a volume in excess of that of the mold cavity, isrelatively small in proportion to the latter. If dry sodium.

silicate in solid form is used, the quantity introduced should be about1/20 of the volume of the cavity. If dry sodium silicate, in grounderpowdered form is used, the volume should be from 1/5 to 1/10 the volumeof the cavity, depending upon the fineness andlightness of the powder.If sodium silicate containing more than 20% of water is used, the volumeintroduced should be proportionately greater. After the closing of themold,' the heating at the above temperature is continued for a period offrom 30 seconds upward according to the size of the nodule. Under theaction of the heat, the material begins to 'intumesce and eventuallyexpands sufliciently to crust 2I which has a relatively smooth, hardenedI surface and which is considerably denser than the frothy or cellularinterior 22 of the mass,

thereby resulting in the nodule shown in Figs. 4

and5. When temperatures above approximately 650, F. are used, thenodules are found to be substantially insoluble in water at roomtemperatures. Some small pieces of sodium silicate intumesced at 800 F.have remained floating on water for more than two years.

Preferably before introducing the silicate into the mold cavities I8 thelatter are washed or coated with a thin solution of lime which not onlypreventsthe resulting nodules from sticking in the mold, but has more orless effect in promoting I the formation of the hardened surface orexterior crust 2|.

The intumesced nodules above described are extremely light and porous,having a density of only two to six pounds per cubic foot, dependingupon the degree of intumescence, as compared to a density of from 10 to16 pounds per cubic foot for ordinary slag wool and sawdust filling andeven higher densities for other insulating materials as heretofore used.On the other hand, said nodules, due to their hardened surfaces orcrusts, are strong and mobile enough to be poured or shoveled, asdistinguished from being blown, into a wall without rupture or dustingdue to abrasion, and are rigid enough not to pack down. Thus, asshown inFig. 10 there may be introduced into the space between the inner andouter portions 23 and 24 of a wall a loose mass 25 of said nodules whichsubstantially completely fills said space. The size of the individualnodules is susceptible of considerable variation. I

between them are points .of resistance to heat flow. 'Moreover, the hardcrusts upon the nodules are effective in stopping the transmission ofheat by radiation, and I have found that the latter effect can beincreased by providing said nodules with reflecting surfaces. :Thesurfaces orv crusts above described, by reason of theirv denseness, havecertain natural reflecting qualities, particularly in the case of thenodule shown in Fig. 8 where the crust I8 is formed by flashing orglazing, but this'effect can be enhanced by applying to them areflective coating such as a varnish or the like. I prefer for thispurpose to use aluminum paint, which may be conveniently applied byspraying, to form a'metallic coating 26, as shown in Fig. 6, and whichmay even be applied to such a nodule as is shown in Fig. 7 to form thedesired hardened surface or crust. Thus the effectiveness as a wallfilling of this material is greatly increased in that the heat flow isnot only retarded by the customary insulating value of the froth ofwhich all the nodules are composed, but it is also greatly retarded bythe fact that attempts of the heat to enter or escape from each noduleare resisted by the surface of the nodule itself.

As shown in Fig. 9, instead of varnishing or painting the surfaces ofthe nodules, a reflecting surface may be provided by enclosing thenodule in a covering of aluminum foil 21.

In addition to those above discussed, the present mode of insulating hasa great advantage in the possibility of preparing the insulatingmaterial at its point of use. In other words, instead of shipping verybulky insulating material to the point of installation, as is nownecessary, it is possible to ship the sodium silicate powder of adensity of about to pounds per cubic foot and, by means of a very simpleapparatus, convert it at the point of installation into the light,porous, hard-crust nodules, suitably coated if desired, which can thenbe at once poured or shovelled into the Walls, partitions, etc.

The advantages above referred to of the hard, dense crusts andreflecting surfaces on nodules used for insulating purposes are notconfined to nodules of intumesced sodium silicate or the like,

but are also obtainable in the case of nodules of other porous heatinsulating material such, for example, as magnesia, asbestos,diatomaceous earth, and the form of mica known as vermiculite.

While the insulating material above described is particularly welladapted for use in connection with the walls of existing buildingstructures, it is by no means limited to such uses as it can toadvantage be incorporated in the walls of such structures during theprocess of building and is also useful for other purposes Whereinsulating jackets are required, as, for example, in oven walls,chimneys, etc.

I claim:

1. An insulating material for the hollow spaces of walls or the likecomprising a loose mass of nodules of intumesced sodium silicate, eachof said nodules having a hardened surface.

2. An insulating material for the hollow spaces of walls or the likecomprising a loose mass of nodules of porous heat insulating material,each of said nodules having an exterior coating of aluminum paint.

3. An insulating material for the hollow spaces of walls and the likecomprising a loose mass of nodules of an intumesced soluble silicate,each of said nodules having a hardened crust coated with aluminum paint.

CHARLES L. NORTON.

